Can't push my changes in Bazaar--need to update libsvn?

For a while, Bazaar was working fine, but now when I push, I get:

Run command: bzr push
Using saved push location: https://<email address hidden>@pl3.projectlocker.com/nano/www/svn
bzr: ERROR: Please upgrade your Subversion client libraries to 1.5 or higher to be able to commit with Subversion mapping v4 (current version is (1, 4, 4, ''))

If I prepend a svn+ in front of the URL, I get:

Run command: bzr push svn+https://<email address hidden>@pl3.projectlocker.com/nano/www/svn
bzr: ERROR: A Subversion remote access command failed: OPTIONS request failed on '/nano/www/svn'

I've been told that I need to update libsvn and then recompile subvertpy. How do I do that?

Note that I am running svn 1.6.9 and subvertpy 0.7.4.

Thanks!

George